Mixer

ABSTRACT

A mixer is provided with a forked tubular stirrer adapted to receive liquids at its upper end and to discharge them into a mixing chamber through tines. An overflow pipe extends through the bottom of the tank and insures an accumulation of liquids in the chamber.

United States Patent [72] Inventors Gunter Friedrich Bartel Lotte Kreiss, Tecklenburg; Martin Klawitter, Rieste, both of Germany [21] Appl. No. 873,003 [22] Filed Oct. 31, 1960 [45] Patented Oct. 12, 1971 [73] Assignee Die Kunststoffburo Osnabruck Dr. Reuter GmbI-I & Co. KG Lotte, Germany [32] Priority Nov. 2, 1968 [3 3] Germany [31] P 18 06 639.2

[54] MIXER 4 Claims, 1 Drawing Fig.

[52] US. Cl 259/8, 259/24, 259/44 [51] Int. Cl 130 15/02, 80 l f 7/20 [50] Field of Search 259/4, 6, 7, 8

[56] References Cited UNITED STATES PATENTS 3,414,245 12/1968 Frazer 259/8 X FOREIGN PATENTS B.26,398 12/1955 Germany 259/8 Primary Examiner-Walter A. Scheel Assistant Examiner-Alan I. Cantor Attorney-Clelle Wv Upchurch ABSTRACT: A mixer is provided with a forked tubular stirrer adapted to receive liquids at its upper end and to discharge them into a mixing chamber through tines. An overflow pipe extends through the bottom of the tank and insures an accu mulation of liquids in the chamber.

MIXER This invention relates generally to mixing devices and more particularly to an apparatus adapted to mix rapidly the chemical reactive components of a synthetic resin such as a polyurethane.

It has been proposed heretofore to construct mixing devices in which a means is provided for introducing one component into the bottom of the mixing chamber and a means for removing the resulting mixture is provided near the top of the chamber. A stirrer is provided in the chamber. Such mixing devices often produce a more uniform mixture than those where all the components are introduced at the top because they insure a sufficient residence time in the mixer. However, devices of this type are not entirely satisfactory because of the problems encountered in sealing openings in the bottom of the mixer against leakage and because they are expensive to build.

It is therefore an object of this invention to provide an improved mixer for reactive chemical components. Another object of the invention is to provide a mixer which insures a residence time therein sufficient for complete mixing without the necessity of introducing a liquid component into the bottom of the mixer. Still another object of the invention is to provide a mixer having a novel and improved stirrer.

Other objects will become apparent from the following description with reference to the accompanying drawing which illustrates one embodiment of the invention.

The foregoing objects and others are accomplished in accordance with this invention, generally speaking, by providing a mixer having a tank with a mixing chamber and an open ended tubular stirrer forked into a plurality of tines which serve as mixing blades. The stirrer is adapted to receive components to be mixed together at its upper end and to discharge them through the open ends of the tines. Usually, only two tines are required but three or more can be provided, if desired. An overflow pipe extends through the bottom of the mixer and terminates with an open end. The overflow pipe is located outside the path of the rotating tines. In a preferred embodiment, the overflow pipe is arranged centrally and vertically in the mixer.

The mixer provided by this invention can be used for mixing various liquids with other liquids or solids. It is particularlyadvantageous for mixing organic polyisocyanates, organic ,compounds having reactive hydrogen atoms such as polyesters, polyethers and the like and other components of a reaction mixture which forms upon chemical reaction a polyurethane plastic. It can be used, for example, to prepare the mixtures described in U.S. Pat. Nos. 2,764,565 and 2,729,618 and similar patents for making polyurethane plastics.

The apparatus of this invention is particularly advantageous because it is of such simple construction but assures substantially uniform mixing of the components together. The use of feedpipes with attendant complicated sealing means is avoided. Because the agitator blades form a fork, space is conveniently provided for extension of an overflow pipe into the center of the mixer. It can, of course, be spaced from the center, if desired, as long as it wont be struck by the stirrer.

By providing a tubular stirrer and means for running incoming components therethrough, a premixing occurs in the stirrer because of the centrifugal action of the stirrer as it rotates.

Referring now to the drawing, a tank or container 1 is provided with a tubular fork-shaped stirrer 2 adapted to be driven through shait3 by motor 4. A pin or spider extends through shaft 3 and the wall of tube 5 to cause the two to be rotated together. The stirrer 2 has a single tube portion 5 extending through the top of tank I and forks into two tines 6 and 7 within tank 1. Passageways l3, l4 and 15 communicate with each other and with tubular portion 5 and tines 6 and 7. The shape of stirrer 2 somewhat resembles an inverted Y. Conduits 8, 9, l0 and 11 conduct components to be mixed together into passageway 13. The components are swirled and mixed with each otheras they pass through passageways l3, l4 and 15. An overflow tube or pipe 12 extends through the bottom wall of tank 1 and terminates in an open end between the tines 6 and 7. Tube 12 is preferably centered in tank ll.

In operation, components are introduced into the passageway 13 of stirrer 2 and flow downwardly through passageways l4 and 15 and into tank 1. Stirrer 2 is continuously rotating at 2000 to 3000 r.p.m. as components, usually liquid, flow therethrough so some mixing occurs in passageways l3, l4 and 15. When the volume of mixture reaches a level above the open end of tube 12, mixture flows out of tank 1 maintaining the level not substantially above the open end of tube 12. The mixture in tank 1 about tube 12 is vigorously agitated as tines 6 and 7 are rotated.

Although the invention has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made by those skilled in the art without departing from the spirit and scope of the invention except as it is limited by the claims.

We claim:

1. A mixing device comprising a container and within said container a tubular fork-shaped stirrer extending as a single open ended tube through the top of said tank and forking into tubular tines having open ends within said tank, means adjacent the top of said tank for introducing components to be mixed into said single tube, and an overflow tubular member for discharging liquid through the bottom of said container extending into said tank and having an open end temiinating between the forked tubular portions of said stirrer.

2. The device of claim 1 wherein said single tube is secured to a drive shaft and the means for introducing components into said stirrer are adapted to introduce the components into the said single tube about said shaft.

3. The device of claim 1 having two tines.

4. A method for mixing liquids which comprises introducing at least two liquids into the top of a tubular fork-shaped stirrer extending as a single open ended tube through the top of a tank and forking into tubular tines having open ends within said tank, rotating said stirrer, allowing liquid to flow from the tines of said stirrer into said tank and collecting liquid mixture from an overflow tubular member extending into said tank and having an open end terminating between the forked tubular portions of said stirrer. 

1. A mixing device comprising a container and within said container a tubular fork-shaped stirrer extending as a single open ended tube through the top of said tank and forking into tubular tines having open ends within said tank, means adjacent the top of said tank for introducing components to be mixed into said single tube, and an overflow tubular member for discharging liquid through the bottom of said container extending into said tank and having an open end terminating between the forked tubular portions of said stirrer.
 2. The device of claim 1 wherein said single tube is secured to a drive shaft and the means for introducing components into said stirrer are adapted to introduce the components into the said single tube about said shaft.
 3. The device of claim 1 having two tines.
 4. A method for mixing liquids which comprises introducing at least two liquids into the top of a tubular fork-shaped stirrer extending as a single open ended tube through the top of a tank and forking into tubular tines having open ends within said tank, rotating said stirrer, allowing liquid to flow from the tines of said stirrer into said tank and collecting liquid mixture from an overflow tubular member extending into said tank and having an open end terminating between the forked tubular portions of said stirrer. 